The high concentration of one tech ETF brings on more risk than the other ETF.The tech sector has had a roller coaster of a year. The tech-heavy Nasdaq Composite, one of the U.S. stock market's three main indexes, lost 20% of its value from the start of the year through April 8. Since then, it has surged over 37% (as of Aug. 5).Despite the volatility, the tech sector is still poised to produce great long-term gains. If you're interested in adding tech stocks to your portfolio, I recommend considering a tech ...